The insulation on a wire often must be stripped therefrom prior to the mechanical crimping or other such engagement of a conductive terminal onto the wire. The amount of insulation to be stripped must be carefully controlled to ensure that adequate mechanical and electrical connection is obtained between the terminal and the conductive portions of the wire. Conversely, the removal of too much insulation can leave a portion of the conductor exposed for possible contact with another electrically conductive lead, contact or the like.
Devices are available that are intended to strip a selected amount of insulation from the end of a wire, and/or to mechanically crimp or otherwise engage a terminal to the exposed conductive lead of the wire. Prior art insulation stripping devices of this type typically operate by inserting the insulated end of a wire into an apparatus. Upon insertion of the wire a specified distance into the apparatus, the wire is clamped to prevent further insertion or withdrawal, and a specified amount of insulation is stripped from the end. The stripping typically is carried out by opposed blades, at least one of which is movable generally orthogonal to the axis of the wire a sufficient amount to sever the insulation. The clamping means and/or the insulation cutting means then are appropriately moved to strip the insulation from the end of the wire. The same device or a similar device may then be employed to mechanically crimp or otherwise engage a terminal onto the exposed conductors at the stripped end of the wire.
The insertion of the wire into the prior art insulation stripper and/or terminal crimper and the removal of the stripped and/or terminated wire from the apparatus typically will be carried out automatically and very quickly. The stripper/crimper devices, however, must achieve a high degree of accuracy and repeatability to meet the quality control standards established by the manufacturers of electrical components and equipment.
A critical component for the accurate and reliable operation of an insulation stripper and/or terminal crimper is the actuation means which triggers the other parts of the device, such as the clamping members, blades and/or crimpers. An actuator that does not initiate movement of the other operative components of the stripper/crimper could easily lead to excessive wire being inserted into the prior art apparatus prior to actuation of the clamping means. This could result in stripping too much insulation from the wire, thereby creating the possibility for short circuits when the terminated wire is placed in an electrical apparatus. Alternatively, the presence of too much wire within the prior art insulation stripping and/or terminal crimping apparatus could urge the wire to a position relative to the blades where at least portions of the conductors would be severed. In still other instances, the axial movement of the clamps and blades of the prior art apparatus relative to one another might not be sufficient to completely remove the insulation from the extreme end of the wire. These and other such problems are most likely to occur with small gauge wires that may not be properly sensed by the actuator means within the prior art stripping/crimping apparatus. As a result, most prior art devices of this type require frequent adjustments.
An example of a known actuating means for an insulation stripper or terminal crimper is described in U.S. Pat. No. 4,601,093 which issued to Cope on July 22, 1986. The apparatus described in U.S. Pat. No. 4,601,093 includes an orifice into which the wire is directed. A sensor pad is spaced in line with the orifice and a selected distance therefrom. The sensor pad of the apparatus shown in U.S. Pat. No. 4,601,093 is attached to a piston which is generally axially aligned with the orifice and the wire passing therethrough, but which extends from the opposite side of the sensor pad. The piston to which the sensor pad shown in U.S. Pat. No. 4,601,093 is attached extends into a pneumatic cylinder. A coil spring within the cylinder is operative to urge the piston ring and the sensor pad outwardly from the cylinder. A wire directed through the orifice of the apparatus shown in U.S. Pat. No. 4,601,093 will be urged into the sensor pad, and is intended to exert an axial force on the sensor pad and the piston extending therefrom sufficiently great to overcome the opposing forces exerted by the coil spring. As a result, the piston of U.S. Pat. No. 4,601,093 is intended to move into the cylinder and against the force of the spring to open the seal around the piston, thereby causing an escape of air from the piston. The lowered pressure in the cylinder is intended to effect operation of a valve via a suitable actuator.
Although the pneumatic principles explained in U.S. Pat. No. 4,601,093 are well known and widely used, the mechanical principles have been difficult to perfect for reliable use in the manufacture of electrical components and devices. In particular, it is necessary to carefully balance the forces exerted by the spring on the piston rod of the apparatus shown in U.S. Pat. No. 4,601,093 with the forces that are likely to be exerted by the wire on the sensor pad. Very small diameter lightweight wires often will not exert adequate forces on the sensor pad to move the piston rod. Attempts to substantially minimize the forces exerted by the spring can result in the spring not exerting sufficient pressure to urge the piston rod out of the cylinder upon completion of a stripping or crimping operation. U.S. Pat. No. 4,601,093 appears to anticipate the sensitivity inherent in the structure by providing a plurality of orifices, sensor pads and spring actuated piston rods for wires of various different gauges. This results in the device being substantially more complex and costly. In view of these inherent problems, devices such as those shown in U.S. Pat. No. 4,601,093 are subject to substantial down time and require adjustments and fine tuning for even minor changes in wire specifications. A device similar to that of U.S. Pat. No. 4,601,093 is shown in West German Published Application No. 3,540,083 which was filed by Kirsten Kabeltech.
In view of the above, it is an object of the subject invention to provide an improved actuator device for an insulation stripper or terminal crimper.
It is another object of the subject invention to provide an actuator for an insulation stripper or terminal crimper that will reliably respond to forces exerted by both large and small gauge wire.
An additional object of the subject invention is to provide an actuator that is responsive to a broad range of wire gauges.
A further object of the subject invention is to provide an actuator for an insulation stripper and/or terminal crimper that is of simple construction.
Yet another object of the subject invention is to provide an actuator for an insulation stripper and/or terminal crimper that avoids the use of piston and cylinder actuator assemblies.